The lawsuit was filed in January 2006. Repligen said in a statement that the U.S. patent of the biologic drug that Bristol sells as Orencia is exclusively licensed to Repligen and owned by the University of Michigan and the United states Department of the Navy.

In addition to the initial $5 million payment, Bristol confirmed to pay royalties at the rate of 1.8 percent for the first $500 million of annual sales, 2 percent for the next $500 million of annual sales and 4 percent of U.S. annual sales in excess of $1 billion for each year from January 1, 2008 until December 31, 2013.

We are very pleased by the settlement of this case which will provide us a substantial new source of revenue... we expect total cash receipts from our Protein A business, Orencia royalties, research and development and other income of greater than $30 million for fiscal year 2009, beginning April 1, 2008 Repligen's chief executive Walter C.Herlihy stated.

According to the US Census Bureau 2.5 million of Americans were diagnosed with rheumatoid arthritis, about 1% of the population.